Dataset contains CMAQv5.3-predicted hourly average concentrations of organic aerosol and other species (HO2, NO, NO3, O3, OH) for Hyytiala, Finland (location of BAECC field campaign) and Centreville, AL, USA (main location of SOAS field campaign) for 2016. How species were created from raw CMAQ output is defined in Table S2 of the paper this data supports. CMAQ v5.3 code is also linked here. The specific configuration of CMAQ is described in the manuscript associated with this data. This dataset is associated with the following publication: Lee, B., E. D'Ambro, F. Lopez-Hilfiker, S. Schobesberger, C. Mohr, M. Zawakowicz, J. Liu, J. Shilling, W. Hu, B. Palm, J. Jimenez, L. Hao, A. Virtanen, H. Zhang, A. Goldstein, H. Pye, and J. Thornton. Resolving Ambient Organic Aerosol Formation and Aging Pathways with Simultaneous Molecular Composition and Volatility Observations. ACS Earth and Space Chemistry. American Chemical Society, Washington, DC, USA, 4(3): 391-402, (2020).

Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are important precursors of secondary organic aerosol (SOA), but the amounts and pathways of SOA generation from these precursors are not well constrained by observations. We propose that the less-oxidized oxygenated organic aerosol (LO-OOA) factor resolved from positive matrix factorization (PMF) analysis on aerosol mass spectrometry (AMS) data can be used as a surrogate for fresh SOA from monoterpenes and sesquiterpenes in the southeastern US. This hypothesis is supported by multiple lines of evidence, including lab-in-the-field perturbation experiments, extensive ambient ground-level measurements, and state-of-the-art modeling. We performed lab-in-the-field experiments in which the ambient air is perturbed by the injection of selected monoterpenes and sesquiterpenes, and the subsequent SOA formation is investigated. PMF analysis on the perturbation experiments provides an objective link between LO-OOA and fresh SOA from monoterpenes and sesquiterpenes as well as insights into the sources of other OA factors. Further, we use an upgraded atmospheric model and show that modeled SOA concentrations from monoterpenes and sesquiterpenes could reproduce both the magnitude and diurnal variation of LO-OOA at multiple sites in the southeastern US, building confidence in our hypothesis. We estimate the annual average concentration of SOA from monoterpenes and sesquiterpenes in the southeastern US to be roughly 2µgm−3. Dataset (csv file) contains CMAQ model predictions for locations in the southeastern US during 2012 and 2013. The species definition file (txt) defines how quantities were obtained from the model. Data in the csv files follows the writesite utility output format (https://github.com/USEPA/CMAQ/tree/5.2.1/POST/writesite). Links to additional datasets are provided. This dataset is associated with the following publication: Xu, L., H. Pye, J. He, Y. Chen, B. Murphy, and N. Ng. Experimental and model estimates of the contributions from biogenic monoterpenes and sesquiterpenes to secondary organic aerosol in the southeastern United States. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 18(17): 12613-12637, (2018).

The relationship between the oxidation state and relative volatility of secondary organic aerosol (SOA) from the oxidation of a wide range of hydrocarbons is investigated using a fast-stepping, scanning thermodenuder interfaced with a high resolution time-of-flight aerosol mass spectrometer (AMS). SOA oxidation state varied widely across the investigated range of parent hydrocarbons but was relatively stable for replicate experiments using a single hydrocarbon precursor. On average, unit mass resolution indicators of SOA oxidation (e.g., AMS f43 and f44) are consistent with previously reported values. Linear regression of H:C vs O:C obtained from parameterization of f43 and f44 and elemental analysis of high resolution spectra in Van Krevelen space both yield a slope of ~0.5 across different SOA types. A similar slope was obtained for a distinct subset of toluene/NOx reactions in which the integrated oxidant exposure was varied to alter oxidation. The relative volatility of different SOA types displays similar variability and is strongly correlated with SOA oxidation state (OSC). On average, relatively low oxidation and volatility were observed for aliphatic alkene (including terpenes) and n-alkane SOA while the opposite is true for mono- and polycyclic aromatic hydrocarbon SOA. Effective enthalpy for total chamber aerosol obtained from volatility differential mobility analysis is also highly correlated with OSC indicating a primary role for oxidation levels in determining the volatility of chamber SOA. Effective enthalpies for chamber SOA are substantially lower than those of neat organic standards but are on the order of those obtained for partially oligomerized glyoxal and methyl glyoxal. This dataset is associated with the following publication: Docherty, K., E. Corse, M. Jaoui, J. Offenberg, T. Kleindienst, J. Krug, T. Riedel, and M. Lewandowski. Trends in the oxidation and relative volatility of chamber-generated secondary organic aerosol. AEROSOL SCIENCE AND TECHNOLOGY. Taylor & Francis, Inc., Philadelphia, PA, USA, 52(9): 992-1004, (2018).

The relationship between the oxidation state and relative volatility of secondary organic aerosol (SOA) from the oxidation of a wide range of hydrocarbons is investigated using a fast-stepping, scanning thermodenuder interfaced with a high resolution time-of-flight aerosol mass spectrometer (AMS). SOA oxidation state varied widely across the investigated range of parent hydrocarbons but was relatively stable for replicate experiments using a single hydrocarbon precursor. On average, unit mass resolution indicators of SOA oxidation (e.g., AMS f43 and f44) are consistent with previously reported values. Linear regression of H:C vs O:C obtained from parameterization of f43 and f44 and elemental analysis of high resolution spectra in Van Krevelen space both yield a slope of ~0.5 across different SOA types. A similar slope was obtained for a distinct subset of toluene/NOx reactions in which the integrated oxidant exposure was varied to alter oxidation. The relative volatility of different SOA types displays similar variability and is strongly correlated with SOA oxidation state (OSC). On average, relatively low oxidation and volatility were observed for aliphatic alkene (including terpenes) and n-alkane SOA while the opposite is true for mono- and polycyclic aromatic hydrocarbon SOA. Effective enthalpy for total chamber aerosol obtained from volatility differential mobility analysis is also highly correlated with OSC indicating a primary role for oxidation levels in determining the volatility of chamber SOA. Effective enthalpies for chamber SOA are substantially lower than those of neat organic standards but are on the order of those obtained for partially oligomerized glyoxal and methyl glyoxal. This dataset is associated with the following publication: Docherty, K., E. Corse, M. Jaoui, J. Offenberg, T. Kleindienst, J. Krug, T. Riedel, and M. Lewandowski. Trends in the oxidation and relative volatility of chamber-generated secondary organic aerosol. AEROSOL SCIENCE AND TECHNOLOGY. Taylor & Francis, Inc., Philadelphia, PA, USA, 52(9): 992-1004, (2018).

This data documents the results of chamber modeling and chemical transport modeling of the contribution of Intermediate Volatility Organic Compounds to mobile-source organic aerosol formation in California. The data show that IVOCs make up a significant fraction of the total source of secondary organic aerosol in urban environments and that mobile sources make up only about one third to half of the total IVOC emissions. Other urban sources of IVOCs were explored. These data are visualized and presented in the figures published in a peer-reviewed manuscript (with corresponding title) in Atmospheric Chemistry and Physics. The raw CMAQ output data are backed up and preserved on the ATMOS supercomputing system at the National Computing Center in Durham, North Carolina. The file location on the ASM server is: /asm/MOD3DEV/bmurphy/Models/cmaq/CMAQ_Ben/Projects/quanyang_181212/data. This dataset is associated with the following publication: Lu, Q., B. Murphy, M. Qin, P.J. Adams, Y. Zhao, H. Pye, C. Efstathiou, C. Allen, and A. Robinson. Simulation of organic aerosol formation during the CalNex study: updated mobile emissions and secondary organic aerosol parameterization for intermediate-volatility organic compounds. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 20(7): 4313–4332, (2020).

This data documents the results of chamber modeling and chemical transport modeling of the contribution of Intermediate Volatility Organic Compounds to mobile-source organic aerosol formation in California. The data show that IVOCs make up a significant fraction of the total source of secondary organic aerosol in urban environments and that mobile sources make up only about one third to half of the total IVOC emissions. Other urban sources of IVOCs were explored. These data are visualized and presented in the figures published in a peer-reviewed manuscript (with corresponding title) in Atmospheric Chemistry and Physics. The raw CMAQ output data are backed up and preserved on the ATMOS supercomputing system at the National Computing Center in Durham, North Carolina. The file location on the ASM server is: /asm/MOD3DEV/bmurphy/Models/cmaq/CMAQ_Ben/Projects/quanyang_181212/data. This dataset is associated with the following publication: Lu, Q., B. Murphy, M. Qin, P.J. Adams, Y. Zhao, H. Pye, C. Efstathiou, C. Allen, and A. Robinson. Simulation of organic aerosol formation during the CalNex study: updated mobile emissions and secondary organic aerosol parameterization for intermediate-volatility organic compounds. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 20(7): 4313–4332, (2020).

Oxidation of the monoterpene Δ3-carene (C10H16) is a potentially important and under-studied source of atmospheric secondary organic aerosol (SOA). We present chamber-based measurements of the speciated gas and particle phases during photochemical oxidation of Δ3-carene. We find evidence of highly oxidized organic molecules (HOM) in the gas phase and relatively low volatility SOA dominated by C7-C10 species. We then use computational methods to develop the first stages of a Δ3-carene photochemical oxidation mechanism and explain some of our measured compositions. We find that alkoxy bond scission of the cyclohexyl ring likely leads to efficient HOM formation, in line with previous studies. We also find a surprising role for the abstraction of primary hydrogens from methyl groups, which has been calculated to be rapid in the α-pinene system, and suggest more research is required to determine if this is more general to other systems and a feature of autoxidation. This work develops a more comprehensive view of Δ3-carene photochemical oxidation products via measurements and lays out a suggested mechanism of oxidation via computationally derived rate coefficients. This dataset is not publicly accessible because: Non-EPA data. It can be accessed through the following means: Please contact Joel Thornton at: thornton@atmos.uw.edu. Format: text files. This dataset is associated with the following publication: D'Ambro, E., N. Hyttinen, K. Møller, S. Iyer, R. Otkjær, D. Bell, J. Liu, F. Lopez-Hilfiker, S. Schobesberger, J. Shilling, A. Zelenyuk, H. Kjaergaard, J. Thornton, and T. Kurten. Pathways to highly oxidized products in the Δ3-Carene + OH system. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 56(4): 2213-2224, (2022).

Oxidation of the monoterpene Δ3-carene (C10H16) is a potentially important and under-studied source of atmospheric secondary organic aerosol (SOA). We present chamber-based measurements of the speciated gas and particle phases during photochemical oxidation of Δ3-carene. We find evidence of highly oxidized organic molecules (HOM) in the gas phase and relatively low volatility SOA dominated by C7-C10 species. We then use computational methods to develop the first stages of a Δ3-carene photochemical oxidation mechanism and explain some of our measured compositions. We find that alkoxy bond scission of the cyclohexyl ring likely leads to efficient HOM formation, in line with previous studies. We also find a surprising role for the abstraction of primary hydrogens from methyl groups, which has been calculated to be rapid in the α-pinene system, and suggest more research is required to determine if this is more general to other systems and a feature of autoxidation. This work develops a more comprehensive view of Δ3-carene photochemical oxidation products via measurements and lays out a suggested mechanism of oxidation via computationally derived rate coefficients. This dataset is not publicly accessible because: Non-EPA data. It can be accessed through the following means: Please contact Joel Thornton at: thornton@atmos.uw.edu. Format: text files. This dataset is associated with the following publication: D'Ambro, E., N. Hyttinen, K. Møller, S. Iyer, R. Otkjær, D. Bell, J. Liu, F. Lopez-Hilfiker, S. Schobesberger, J. Shilling, A. Zelenyuk, H. Kjaergaard, J. Thornton, and T. Kurten. Pathways to highly oxidized products in the Δ3-Carene + OH system. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, USA, 56(4): 2213-2224, (2022).

This dataset provides airborne in situ observations of submicron organic aerosol (OA) mass concentrations during the first (mid-2016) and second (early-2017) global deployments of the Atmospheric Tomography Mission (ATom), as well as modeled submicron OA mass concentrations along the flight tracks from global chemistry models that implement a variety of commonly used representations of OA sources and chemistry. In situ observations include non-refractory submicron aerosols measured by the High-Resolution Aerosol Mass Spectrometer (HR-AMS), aerosol volume concentrations measured by the Aerosol Microphysical Properties package (AMP), black carbon mass content measured by the Single Particle Soot Photometer (NOAA SP2), and refractory and non-refractory aerosol composition measured by the Particle Analysis By Laser Mass Spectrometry (PALMS). Both observed and modeled data are provided at a 60-second temporal resolution. The data are provided in netCDF format.